haha nhiều lắm bạn à GIẢ sử có các số \(ab^2+cd^2=ba^2+dc^2\)với \(a,b,c,d\varepsilonℕ^∗\)

\(\Leftrightarrow(a-b)(a+b)=(d-c)(c+d)\)

tìm các bộ số này rất dễ chẳng hạn như \((5-1)(5+1)=(7-5)(7+5)\)

\(\Leftrightarrow51^2+57^2=15^2+75^2\)

11^2+22^2=11^2+22^2

22^2+33^2=22^2+33^2

......

88^2+99^2=88^2+99^2

Câu này hay nhỉ

Nhưng mak khó quá mk ko nghĩ ra.

Xin lỗi bn nhé!

\(\left(9-4x\right)^3=125\)

\(\left(9-4x\right)^3=5^3\)

\(\Rightarrow9-4x=5\)

\(4x=9-5\)

\(4x=4\)

\(x=4\div4\)

\(x=1\)

Vậy x = 1

=))

C2 :

\(2\cdot3^{x+2}+4\cdot3^{x+1}=10\cdot3^{2019}\)

\(2\cdot3\cdot3^{x+1}+4\cdot3^{x+1}=10\cdot3^{2019}\)

\(6\cdot3^{x+1}+4\cdot3^{x+1}=10\cdot3^{2019}\)

\(\left(6+4\right)\cdot3^{x+1}=10\cdot3^{2019}\)

\(10\cdot3^{x+1}=10\cdot3^{2019}\)

\(\Rightarrow x+1=2019\)

\(x=2019-1\)

\(x=2018\)

Vậy x = 2018

Chắc sai =))

a: =25x100-150=2500-150=2350

c: \(=520:\left\{515\cdot25\right\}\)

=104/2575

a ) 475

b) 269

c ) 27000

d ) 2800

a) \(86+375+14\)

\(=\left(86+14\right)+375\)

\(=100+375\)

\(=475\)

b) \(72+69+128\)

\(=\left(72+128\right)+69\)

\(=200+69\)

\(=269\)

c) \(25\cdot5\cdot4\cdot27\cdot2\)

\(=\left(25\cdot4\right)\cdot\left(5\cdot27\right)\cdot2\)

\(=100\cdot135\cdot20\)

\(=200\cdot135\)

\(=27000\)

d) \(28\cdot64+28\cdot36\)

\(=28\cdot\left(64+36\right)\)

\(=28\cdot100\)

\(=2800\)

a, 86+375+14

=(86+14)+375

=100+375

=475

b, 72+69+128

=(72+128)+69

=200+69

=269

c, 25.5.4.27.2

=(25.4)(5.2).27

=100.10.27

=1000.27

=27000

d, 28.64+28.36

=28(64+36)

=28.100

=2800

\(86+357+14=457\)

\(72+69+128=275\)

\(25\cdot5\cdot4\cdot27\cdot2=27000\)

\(28\cdot64+28\cdot36=28\left(64+36\right)=2800\)

a) \(86+357+14=\left(86+14\right)+357=100+357=457\)

b) \(72+69+128=\left(72+128\right)+69=200+69=269\)

c) \(25.5.4.27.2=\left(25.4\right).\left(5.2\right).27=100.10.27=27000\)

d) \(28.64+28.36=28\left(64+36\right)=28.100=2800\)